Hygienic article with temporarily attached side panels

ABSTRACT

A hygienic article having side panels extending outward in a lateral direction from either of said front or back waist region. Each side panel comprises at least two material segments which are connected to each other by a lap seam wherein said material segments define a distal segment and a proximal segment in the lateral direction. On the distal edge of each side panel a fastening member is placed which is capable of securing said side panels to the front or back waist region such that the hygienic article assumes a pant like shape. The material segments which form the side panels are attached to each other by the lap seam in such a way that when the side panels are folded back towards the longitudinal centreline of the hygienic article, the materials are attached to each other in the lap seam such that the most distal material segment is placed closer towards the inner or outer surface of the hygienic article than the more proximal material segment attached to said most distal segment. Furthermore, at least one temporary attachment is situated on the lap seam or between the lap seam and the longitudinal outer edge of the chassis.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a hygienic article having an innersurface facing the user during use, an outer surface facing away fromthe user during use and optionally an absorbent core therebetween. Thehygienic article also comprises a front waist region and a back waistregion with a crotch region connecting said front and back waist regionsalong a longitudinal direction and has side panels extending outward ina lateral direction from either of said front or back waist region. Eachside panel comprises at least two material segments which are connectedto each other by a lap seam wherein said material segments define adistal segment and a proximal segment in the lateral direction. On thedistal edge of each side panel a fastening member is placed which iscapable of securing said side panels to the front or back waist regionsuch that the hygienic article assumes a pant like shape. Said sidepanels are folded back towards the hygienic articles longitudinalcentreline before use and attached to the inner or outer surface by atleast one temporary attachment.

BACKGROUND ART

Absorbent products comprising side panels are today quite common on openabsorbent articles and known to those skilled in the art. By using sidepanels instead of fastening tabs it is possible to make the chassis ofthe product narrower which saves both material cost as well as makes theproduct more pleasant to wear since the product doesn't cover as much ofthe users' skin. Another advantage is the fact that side panels caneasily be tailored to have desired characteristics such as elasticity orbreathability.

A drawback with side panels is the production problem. Absorbentproducts are produced at very high speeds and side panels extendingoutwards in a lateral direction can cause problems such as jamming ofthe machine with the material pieces. This problem can be overcome bytemporarily attaching the loose distal ends of the side panels in theprocess, said attachments at a later stage being released by the userwhen putting on the article. Such temporary attachments are described ine.g. WO2007/071267 and WO02/26183.

As mentioned above, side panels can be tailored to have specificcharacteristics such as elasticity or breathability. Such side panelsare often composed of at least two material segments. An advantage ofcombining different material segments is that elastic materials andbreathable materials tend to be more expensive than simple nonwovenlaminates and the amount of such expensive material used can thus bereduced. A further reason may be that elastic materials as well asbreathable materials can have a poor shear strength and if a largematerial piece is used the side panel might not be able to withstand theforces induced in the panel during use. Examples of such side panels canbe found in US 20030109844, EP 1133967 and WO 2002049567.

A common problem with these side panels is that the attachment betweenthe different material segments can provide a weakness in the side panelconstruction. This is normally not a very large problem if the differentmaterial segments are attached to each other by lap seams, which meansthat the lap seams will be influenced by a shear force rather than apeel force when the article is used. A lap seam has generally higherresistance to breaking when subjected to shear forces than whensubjected to peeling forces.

An absorbent article having side panels comprising two material segmentswhere said side panel is temporarily attached during production andtransportation is disclosed in EP 1 418 874. The material segments ofthe side panels are connected by lap seams and are folded in a Zconfiguration and temporarily attached in the Z configuration. When theuser pulls the side panels outwards to release the temporary attachment,shear forces are achieved in both the lap seam and in the temporaryattachments. If one desires to break an attachment it is advantageous tohave a peel force since it is not as strong as a shear force if appliedonto the same attachment. Thus, if a shear force is achieved in anattachment which is intended to break this will be a disadvantage sincethe direction of force is unfavourable and a higher force is requiredwhich might lead to tearing of the materials attached by said temporaryattachments. There is also a certain complexity in the foldingarrangement of the side panels which might cause productiondifficulties.

In view of these documents there is still a need for a product which hasside panels comprising more than one material segment where the userdoesn't risk tearing the materials attached by the temporary attachmentwhen releasing the side panels or to break the lap seam attaching thetwo material segments together. At the same time the production processof articles with such side panels should be easy without too manycomplex processing steps.

SUMMARY OF THE INVENTION

The present invention provides a hygienic article having an innersurface facing the user during use, an outer surface facing away fromthe user during use and optionally an absorbent core therebetween; saidhygienic article comprising a front waist region and a back waist regionwith a crotch region connecting said front and back waist regions alonga longitudinal direction; said absorbent article comprising side panelsextending outward in the lateral direction from either said front orback waist region; said side panels comprising at least two materialsegments which are connected to each other by a lap seam; said materialsegments defining a distal segment and a proximal segment in the lateraldirection; said side panels each having at least one fastening member attheir distal ends which fasteners are capable of securing said sidepanels to the front or back waist region such that the absorbent articleassumes a pant like shape; said side panels are folded back towards theabsorbent articles longitudinal centreline before use and attached tothe inner or outer surface by at least one temporary attachment wherebythe material segments which form the side panels are attached to eachother by the lap seam in such a way that when the side panels are foldedback towards the longitudinal centreline of the hygienic article thematerials are attached to each other in the lap seam such that the mostdistal material segment is placed closer towards the inner or outersurface of the hygienic article than the more proximal material segmentattached to said most distal segment and that at least one temporaryattachment is situated on the lap seam or between the lap seam and thelongitudinal outer edge of the chassis.

This placement ensures that when severing the temporary attachments afavourable load condition is achieved such that the force exerted on thelap seam will be essentially a shear force and not a peel force. At thesame time the force needed to break the temporary attachments is a peelforce which ensures that the materials attached by the temporaryattachment will not break since a bond breaks easier when subjected to apeel force than to a shear force.

Another advantage is that the product only requires one folding step inthe process which reduces the risk of machine jamming compared to whenthe side panels have been folded in a more complex manner. Thusaccording to another embodiment of the invention the side panels areonly folded once in the lateral direction.

According to another embodiment of the invention each side panelcomprises at least three material segments. This could be an advantageif it is desired to introduce a material into the side panels which isvery expensive, allowing for a smaller piece to be used, alternativelythe material introduced is not able to resist strong shear forces and alarge material segment would thus cause a weakness in the side panelconstruction. Using three or more material segments thus allows for animproved tailoring of the side panel characteristics as compared to aside panel composed of only two material segments.

At least one of the material segments in a side panel may be abreathable material. Non-breathable materials tend to increase humidityin the area where the materials are placed in close proximity to theskin of a user. If a non-breathable material is replaced by a breathablematerial, said breathable materials are able to transport the moistureand humidity caused by perspiration away from the skin surface of theusers. Breathable materials thus provide superior comfort to the usersas compared to products which do not have breathable areas.

It is also possible to make at least one of the material segments in aside panel from an elastic material. Insertion of an elastic materialinto the side panels enables the hygienic product to better conform tothe user when the user moves around. Since the diameter of the waistarea greatly alters when sitting or standing, a piece of elasticmaterial can ensure that the product doesn't slip down when a userstands up or causes red marks when the user sits down. Simply because amaterial is elastic it is not excluded that it can also be breathable,thereby combining the advantages of breathability and elasticity in thesame side panel.

The fastening member of the side panel may be a hook fastener. Hookfasteners are advantageous to use since they allow for multiple openingand reclosing of the hygienic article without damaging the article. Mostoften a landing member is used onto which the hook fastener is attachedbut it is also possible to attach the hook fastener directly onto theouter surface of the hygienic article if said surface is made of anonwoven material which can significantly reduce the cost of thehygienic article.

According to another embodiment of the invention the temporaryattachments are placed between the fastening member situated on the mostdistal edge of the side panel and at least 1 cm from the longitudinalside edge of the chassis, preferably the placement should be between thefastening member and at least 3 cm from the longitudinal side edge ofthe chassis. This placement ensures that when a user pulls open thetemporary attachments they can easily see if the side panels arecompletely released or if some temporary attachments still remain whichneed to be released. A problem associated with unreleased temporaryattachments is that if the user puts on a product where a temporaryattachment has not been released, said attachment is not designed to besufficiently strong to withstand the pulling forces induced in the sidepanel during use. Thus, the unreleased temporary attachment will mostprobably release when the article is being worn and the product willslip down the users' waist. This might cause discomfort to the user andthere is also a greater risk of leakage since the product is not keptproperly in place.

According to a further embodiment of the invention a force of 0,5-10 Nis required to rupture the temporary attachments, preferably a force of0,5-7 N is required, more preferably a force of 1-5 N is required andmost preferably a force of 2-3 N is required. The force is measuredaccording to ASTM D 1876-72 on 25 mm wide samples. In order to withstandthe forces in the production process and during transportation it isdesired that the force necessary to break said temporary attachmentsshould be at least 0,5 N. However, if the temporary attachments are toostrong there is a risk of tearing the materials attached by saidtemporary attachments when the attachments are to be released. The forcerequired to break said temporary attachments should thus preferably be10N or lower.

According to an embodiment of the invention each side panel consists ofthree material segments where the most distal lap seam has the mostdistal material segment placed closer to the absorbent article than themore proximal material segment and the most proximal lap seam has themost proximal material segment placed closer to the absorbent articlethan the more distal material segment and where the temporary attachmentis placed on the most distal lap seam or between the most distal lap andthe most proximal lap seam.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail below with referenceto the embodiments shown in the appended drawings, in which

FIG. 1 shows an absorbent article according to one embodiment of theinvention from the side intended to be directed towards a user duringuse;

FIG. 2 shows a cross sectional view along the line 1-1 of FIG. 1;

FIG. 3 shows an embodiment which is not part of this invention, the lapseam clearly breaks when the side panel is pulled to release thetemporary attachment due to the unfavourable load condition caused byplacing the distal segment farther away from the inner surface in thelap seam with respect to the proximal segment;

FIG. 4 shows an embodiment according to this invention, the lap seamdoes not break since the direction of the force in the lap seam differsfrom the one shown in FIG. 3 and hence a more favourable load conditionis achieved;

FIG. 5 shows a further embodiment according to the present inventionwhere the side panel consists of three material segments;

FIG. 6 shows still a an alternative embodiment according to theinvention where the side panel consists of three material segments wherethe segments are placed a bit differently in relation to each other ascompared to FIG. 5;

FIG. 7 shows a lap seam as intended by the present invention and whenthe material segments are pulled in different directions a shear forceis induced in the lap seam attachment; and

FIG. 8 shows an abutting seam which is not covered by the presentinvention and in which a peel force is induced in the abutting seamattachment when the two material segments are pulled in differentdirections.

DEFINITIONS

As used herein, “hygienic articles” refer to articles includingabsorbent articles and absorbent or non-absorbent holders for absorbentarticles or absorbent inserts which may or may not be reusable.

“Absorbent articles” refer to diapers, incontinence articles, sanitarypanties as well as any other similar product which is suitable to usefor absorbing urine or menstrual fluids.

“Shear force” refers to a force which is applied to materials in a planegenerally parallel to the plane of attachment of the materials.

“Peel force” refers to a force applied at an angle of 70 degrees or moreto the attachment between the materials.

“Inner surface” is intended to mean a surface made up of any material onthe surface of the hygienic article which is facing the user during use.Structural elements which are normally considered to be part of theinner surface in an absorbent article are topsheets and standinggathers.

“Outer surface” refers to the material forming the cover of the hygienicarticle which faces the user's garment during use. An outer surface isoften referred to as a backsheet but could include other structuralelements which form part of the outer surface of a hygienic article.

A “fastening member” is herein defined as a fastener which is capable oftemporarily attaching the side panels to the outer surface of theabsorbent article such that the article assumes a pant like shape.

By “lap seam” a fastening configuration is intended wherein the twomaterial pieces are placed in an overlapping arrangement and thereafterpermanently attached to each other. A permanent attachment is anattachment which is not intended to open during normal use and if itbreaks, the attachment cannot be reattached. In FIG. 7 a lap seam isshown whereas the abutted seam in FIG. 8 is not intended to be coveredby the definition lap seam.

A “side panel” is a portion of the article which extends in a lateraldirection beyond one or both the longitudinal side edges of the chassisin one of the waist areas of the hygienic article.

The chassis is defined as the part of the hygienic article whichcomprises both outer surface material as well as inner surface material.

A “temporary attachment” is an attachment which is sufficiently strongto withstand a pulling force which might arise during, for exampleproduction and shipping, whilst at the same time being sufficiently weakto easily break without damaging the materials which are attached bysaid attachment. When a temporary attachment is released it cannot bereattached.

DETAILED DESCRIPTION

FIG. 1 shows a diaper 1 seen from the inner side which is the side ofthe diaper intended to face the user during use of the diaper. Thediaper 1 comprises an inner surface 2 and an outer surface 3 with anabsorbent core 4 situated between the two surfaces. The diaper has alongitudinal direction y and a lateral direction x. The diaper comprisesa front region 5, a back region 6 and a crotch region 7 connecting saidfront and back regions in a longitudinal direction y. Side panels 10 areattached to the diaper along the longitudinal side edges 9 of the backregion 6. The side panels 10 are folded inwards towards a longitudinalcentreline 8 of the diaper and have temporary attachments 11 to theinner surface 2 of the diaper 1, the temporary attachments in the shownexample being in the form of ultrasonic bonds. The side panels 10 arecomposed of two material segments 12, 13 which segments are connected bya lap seam 14 which is ultrasonically bonded. The temporary attachments11 of the side panels 10 are placed in rows of two individualattachments along a lateral direction x of the side panels 10, where oneof the rows is situated between the longitudinal outer edge 9 of thediaper and the lap seam 14 and the second row is situated between thelap seam 14 and the distal edge 15 of the side panel 10.

FIG. 2 shows a cross sectional view along the line 1-1 of FIG. 1. Thediaper in FIG. 2 shows a backsheet 22 (outer surface 3), a topsheet 20(inner surface 2), standing gathers 21 (inner surface 2) and anabsorbent core 4. Side panels 10 which each comprise two materialsegments 12, 13 are permanently attached to the diaper 1 between thetopsheet 20 and the backsheet 22 materials and are folded inwardstowards a longitudinal centreline 8 of the diaper 1. On the most distaledge 15 of the side panels 10 a hook member 16 is attached. The materialsegments 12, 13 forming the side panels 10 are attached to each other bythe lap seam 14 in such a way that when the side panels 10 are folded intowards the longitudinal centreline 8 of the diaper 1 the materials 12,13 are attached to each other in the lap seam 14 such that the mostdistal material segment 12 is placed closer towards the inner surface 2of the diaper 1 than the more proximal material segment 13 attached tosaid most distal segment 12. The lap seam 14 connects the two materialssegments 12, 13 by way of an ultrasonic bond. Temporary attachments 11in the form of ultrasonic bonds are used to attach each side panel 10 inthe folded configuration. As shown in FIGS. 1 and 2, the temporaryattachments 11 are placed between the hook member 16 and the lap seam 14as well as between the lap seam 14 and the longitudinal side edge 9 ofthe diaper chassis. In the example, the temporary attachments 11 form anattachment between the side panels 10 and standing gather material 21found on the inner surface 2 of the diaper.

The inner surface 2 can comprise a typical topsheet material such as anonwoven material, e.g. spunbond, meltblown, carded, hydroentangled,wetlaid etc. Suitable nonwoven materials can be composed of naturalfibers, such as woodpulp or cotton fibres, man-made fibres, such aspolyester, polyethylene, polypropylene, viscose, rayon etc. or from amixture of natural and man-made fibres. The inner surface material 2 mayfurther be composed of tow fibres, which may be bonded to each other ina bonding pattern, as e.g. disclosed in EP-A-1 035 818. Further examplesof inner surface materials 2 are porous foams, apertured plastic filmsetc. The materials suited as inner surface materials 2 should be softand non-irritating to the skin and if said inner surface is a topsheet20 it should be readily penetrated by body fluid, e.g. urine ormenstrual fluid. The inner surface may further be different in differentparts of the absorbent article. Any part of the inner surface 2 that isconstituted by a barrier structure such as a standing gather or a faecespocket may be liquid-impermeable or at least show some degree ofresistance to liquid penetration.

The outer surface 3 may be uniform or different in different parts ofthe hygienic article. At least in the area of the absorbent core 4, theouter surface 3 comprises a liquid impervious material, a thin plasticfilm, e.g. a polyethylene or polypropylene film, a nonwoven materialcoated to be a liquid impervious material, a hydrophobic nonwovenmaterial, which resists liquid penetration, or a laminate of a plasticfilm and a nonwoven material. The outer surface material 3 may bebreathable so as to allow vapour to escape from the absorbent core,while still preventing liquids from passing therethrough. Examples ofbreathable outer surface materials are porous polymeric films, nonwovenlaminates of spunbond and meltblown layers and laminates of porouspolymeric films and nonwoven materials. Preferably, the outer surface 3comprises a nonwoven material on the garment-facing surface thereof toimprove appearance and provide a more textile impression.

The “absorbent core” 4 is the absorbent structure disposed between thetwo surfaces 2, 3 of the absorbent article in at least the crotch region7 thereof. The absorbent core 4 can be of any conventional kind.Examples of commonly occurring absorbent materials are cellulosic fluffpulp, tissue layers, highly absorbent polymers (so calledsuperabsorbents), absorbent foam materials, absorbent nonwoven materialsor the like. It is common to combine cellulosic fluff pulp withsuperabsorbent polymers in an absorbent core. Superabsorbent polymersare water-swellable, water-insoluble organic or inorganic materialscapable of absorbing at least about 10 times their own weight of anaqueous solution containing 0.9 weight percent of sodium chloride.Organic materials suitable for use as superabsorbent materials caninclude natural materials such as polysaccharides, polypeptides and thelike, as well as synthetic materials such as synthetic hydrogelpolymers. Such hydrogel polymers include, for example, alkali metalsalts of polyacrylic acids, polyacrylamides, polyvinyl alcohol,polyacrylates, polyacrylamides, polyvinyl pyridines, and the like. Othersuitable polymers include hydrolyzed acrylonitrile grafted starch,acrylic acid grafted starch, and isobutylene maleic anhydride copolymersand mixtures thereof. The hydrogel polymers are preferably lightlycross-linked to render the material substantially water insoluble.Preferred superabsorbent materials are further surface cross-linked sothat the outer surface or shell of the superabsorbent particle, fibre,flake, sphere, etc. possesses a higher crosslink density than the innerportion of the superabsorbent. The superabsorbent materials may be inany form which is suitable for use in absorbent composites includingparticles, fibres, flakes, spheres, and the like.

A high liquid storage capacity is provided by the use of high amounts ofsuperabsorbent material. For an absorbent core 4 comprising a matrix ofhydrophilic fibres, such as cellulosic fibres, and superabsorbentmaterial, the proportion of superabsorbent material is preferablybetween 10 and 90% by weight, more preferably between 30 and 70% byweight.

It is conventional for absorbent articles to have absorbent corescomprising layers of different properties with respect to liquidreceiving capacity, liquid distribution capacity and storage capacity.The thin absorbent bodies, which are common in for example baby diapersand incontinence guards, often comprise a compressed, mixed or layeredstructure of cellulosic fluff pulp and superabsorbent polymers. The sizeand absorbent capacity of the absorbent core 4 may be varied to suitdifferent uses, such as infants or adult incontinent persons.

The absorbent core 4 may further include an acquisition distributionlayer placed on top of the primary absorbent body, which is adapted toquickly receive and temporarily store discharged liquid before it isabsorbed by the primary absorbent core. Such acquisition distributionlayers are well known in the art and may be composed of porous fibrouswadding or foam materials. The side panels 10 are the material pieceswhich extend in a lateral direction x beyond the longitudinal side edges9 of the chassis in one or both of the waist areas 5, 6 of the hygienicarticle. In this respect the chassis is intended as the part of theproduct which comprises at least one inner surface 2 and at least oneouter surface 3, where said surfaces 2, 3 comprise different materialsas discussed above. Accordingly, the side panels 10 may have a portionwhich comprises the outer surface material 3 which extends beyond thelongitudinal side edge 9 of the inner surface material 2, or vice versa.The side panels 10 comprise at least two material segments 12, 13extending in the lateral direction x.

The side panels 10 are for example made from a nonwoven material or anonwoven material laminate. Preferably a soft nonwoven forms the insideof the panels which is intended to be in direct contact with the skin ofthe user.

A suitable nonwoven material can be a spunbond material of e.g.polypropylene or polyethylene fibres. Conjugate fibres may also be used.Another suitable nonwoven material is formed from a carded thermobondedmaterial of e.g. polypropylene, polyester or conjugate fibres.

In a further embodiment at least one of the material segments formingthe side panels 10 is breathable so as to allow vapour to escape fromthe surface of the skin of the user. Examples of breathable outersurface materials are microporous and/or perforated polymeric films,nonwoven laminates of spunbond and meltblown layers and laminates ofmicroporous and/or perforated polymeric films and nonwoven materials.

In still a further embodiment at least one of the material segmentsforming the side panels 10 is an elastic web material, such as elasticfilm, an elastic nonwoven, an elastic laminate or the like. The elasticlaminate may be a laminate of two or more nonwoven layers, two or morefilm layers or a combination of film and nonwoven layers.

The elastic film may be of any suitable elastic polymer, natural orsynthetic. Some examples of suitable materials for the elastic film arelow crystallinity polyethylenes, metallocene-catalyzed low crystallinitypolyethylene, ethylene vinyl acetate copolymers (EVA), polyurethane,polyisoprene, butadiene-styrene copolymers, styrene block copolymers,such as styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS),or styrene/ethylene-butadiene/styrene block copolymer. Blends of thesepolymers may also be used as well as other modifying elastomeric ornon-elastomeric materials.

Examples of elastic laminates suitable for forming said elastic regionsare any elastic laminate known in the art. One group of elasticlaminates are so called “stretch-bonded” laminates, in which the elasticlayer is stretched in at least one direction before laminating it withone or more inelastic layers. After the tension is removed from theelastic layer it can freely retract to its untensioned state, and theinelastic layer(s) laminated thereto become gathered, giving athree-dimensional puckering.

Another group of elastic laminates are so called “neck bonded”laminates, which refer laminates in which an elastic material is bondedto a non-elastic material while the non-elastic member is extended underconditions reducing its width or necked. “Neck bonded laminate” refersto a composite material having at least two layers in which one layer isa necked, non-elastic layer and the other layer is an elastic layer. Thelayers are joined together when the non-elastic layer is in an extendedcondition.

A further group of elastic laminates are disclosed in for exampleWO/047488, in which inelastic nonwoven layers are laminated to anelastic film layer, and the laminate is stretched above the point offailure of the nonwoven materials, so that the inelastic layers break.

Examples of elastic laminates are described in EP-B-0 646 062, WO98/29251, WO 03/000165 and U.S. Pat. No. 5,226,992. Examples ofcommercially available elastic laminates are Fabriflex 306 fromTredegar, PK 6358 from Nordenia and GP 403 and GP 401 from GoldenPhoenix Fiberweb.

Alternatively the elastic material segments comprise one or more elasticthreads or strips contractably affixed between web material layers.

Side panels 10 which combine the elastic material segment with abreathable material segment are also envisioned in the presentinvention. The breathable segment in the side panels may be a separatematerial segment or the elastic material segment may in itself bebreathable whereby the two characteristics are combined in one materialsegment.

On the most distal edge 15 of the side panels 10 a mechanical fastener16 is placed which is able to engage with another element placed on theouter side 3 of the hygienic product in the waist region opposed to thewaist region carrying the side panels. Hook-and-loop fasteners are themost commonly used fasteners today.

A “hook-and-loop fastener” refers to complementary fastening meanshaving a “hook” portion and a “loop” portion and which are refastenable.The term “hook” as used herein refers to any element capable of engaginganother element, the so called “loop” portion. The term “hook” is notlimited to only “hooks” in a narrow sense, but rather encompasses anyform of engaging elements, whether unidirectional or bi-directional. Theterm “loop” is likewise not limited to “loops” in a narrow sense, butalso encompasses any structure capable of engaging with a “hook”fastener. Examples of “loop” materials are fibrous structures, likenonwoven materials. Hook-and-loop fasteners are for example availablefrom Velcro, USA.

Alternatively the fastening member is an adhesive fastening member suchas a tape tab, wherein the external surface of opposite belt member maybe of a material to which the tape can adhere, as for example describedin WO 01/00129.

Further examples of mechanical fasteners are button and holes or buttonloops, snap fasteners and the like. The buttons can either be fastenedto the belt or to the garment.

The lap seam 14 can be either a single line of attachment, completelycovering in the region where the materials are joined or it can be aplurality of dots which join the material segments together in theiroverlapping configuration. The shape of attachment is not essential tothis invention but due to the permanent nature of the lap seam said seamshould be sufficiently strong to withstand any shear forces exerted inthe panel during normal use without breaking.

An important feature of the invention to accomplish the desired loadcondition when breaking the temporary attachments is the order in whichthe material segments making up each side panel have been attached toeach other in the lap seams. Accordingly, it is critical that thematerial segments are placed in an order so that when seen in adirection towards the inner surface of the article, the folded-in sidepanels have a more distal segment of each side panel positioned beneaththe contiguous segment of the side panel in the connecting lap seam. Inthe folded-in configuration of the side panels that is shown in FIGS.1-6., the most distal segment of each side panel will be the segmentthat is placed closest to the longitudinal centre line 8 of the article.Hence, this will be the material segment labelled 12 if FIGS. 1 and 2.Since the configuration of each lap seam 14 in FIGS. 1 and 2 is such,that the most distal material segment 12 is placed closer towards theinner 2 or outer surface 3 of the hygienic article 1 than the moreproximal material segment 13 attached to said most distal segment 12when the side panels 10 are folded in towards the longitudinalcentreline 8 of the hygienic article 1, more favourable load conditionsare achieved in the lap seam 14 when peeling apart the temporaryattachments 11. These favourable load conditions differ from the priorart arrangements where the lap seam 14 was exposed to a peel force Dinstead of the shear force C arising in the arrangement according to theinvention. Thus, the invention allows for the lap seam 14 to be lessrobust than was previously possible.

As can be seen in the experiments conducted below, the differencebetween the forces necessary to break an attachment by using shear forceC instead of peel force D is about 75%, where the shear force C is about75% stronger than the peel force D. In view of this, a lap seam 14 canbe designed which is weaker than before. This means that both productiontime, for example quicker welding step, and material, for example lessadhesive used, can be saved, thus reducing production costs. Moreover, astronger seam is generally stiffer and less conformable than a weakerseam implying that the weld may cause comfort problems to a user of thehygienic article. However, it is preferred that the lap seam 14 is ableto withstand the same forces as the material segments it combineswithout breaking. The type of attachment may be of any suitable type ofbonding such as an adhesive, thermal, weld, ultrasonic, crimped orstitched bond.

The temporary attachments 11 according to various embodiments areintended to hold the side panels against the inner 2 or outer surface 3of the hygienic article 1 during transportation. Temporary attachments11 are such that they are sufficiently strong to withstand a pullingforce which might arise, for example during production and shipping,whilst at the same time being sufficiently weak to easily break withoutdamaging the materials which are attached by said attachment.

The temporary attachments 11 can be either a dot or a plurality of dotswhich hold the side panel 10 in place. In an alternative embodiment thetemporary attachments 11 can be either a single line of attachment or itcan be several lines along the lateral direction of the side panel. Thetype of attachment may be of any suitable type of bonding such as anadhesive, thermal, weld, ultrasonic or mechanical bonds such as crimpingor needling.

The shape or type of the temporary attachment 11 is not essential tothis invention as long as it is sufficiently strong to hold the sidepanels in place during production and transportation. However, theplacement of the temporary attachment 11 is a very important feature ofthis invention.

As previously mentioned at least one temporary attachment 11 should beplaced on the lap seam 14 or between the lap seam 14 and thelongitudinal outer edge of the chassis 9. This is applicable to alltypes of side panels 10 consisting of two or more material segments 12,13, 53, 54, 55, as depicted in FIGS. 2 and 5, when the material segments12, 13, 53, 54, 55 which form the side panels 10 are attached to eachother by lap seams 14, 56, 57 in such a way that when the side panels 10are folded in towards the longitudinal centreline 8 of the hygienicarticle 1 the materials 12, 13, 53, 54, 55 are attached to each other inthe lap seams 14, 56, 57 such that the more distal material segment 12,53, 54 is placed closer 51 towards the inner 2 or outer surface 3 of thehygienic article 1 in said lap seam 14, 56, 57 than the more proximalmaterial segment 13, 54, 55 attached to said more distal segment 12, 53,54. However, in an alternative embodiment, as depicted in FIG. 6, thethree material segments 63, 64, 65 which form the side panels 10 areattached to each other by lap seams 60, 61 in such a way, that when theside panels 10 are folded back towards the longitudinal centreline 8 ofthe hygienic article 1 the materials 63, 64, 65 are attached to eachother in the most distal lap seam 60 such that the most distal materialsegment 63 is placed closer towards the inner 2 surface of the hygienicarticle 1 than the central material segment 64 attached to said mostdistal segment 63, and in the more proximal lap seam 61 the mostproximal material segment 65 is placed closer towards the inner 2surface of the hygienic article 1 than the central material segment 64attached to said most proximal material segment 65. In an embodimentsuch as the one depicted in FIG. 6, the temporary attachment 11 shouldbe placed on the most distal lap seam 60 or on the central materialsegment 64.

If the side panel 10 has only one lap seam 14 or all lap seams 14 havethe material segments 12, 13, 53, 54, 55 layered in the same manner asthe most distal lap seam 14 then the placement of the temporaryattachment 11 is not crucial. Even though it is not crucial to theinvention, it has been found advantageous to place the temporaryattachments 11 between the fastening member 16 situated on the mostdistal edge of the side panel 15 and at least 1 cm from the longitudinalside edge of the chassis 9, preferably the placement should be betweenthe fastening member 16 and at least 3 cm from the longitudinal sideedge of the chassis 9. This placement ensures that when a user pullsopen the temporary attachments 11 they can easily see if the side panels10 are completely released or if some temporary attachments 11 stillremain which need to be released. A problem associated with unreleasedtemporary attachments 11 is that if the user puts on a product where atemporary attachment 11 has not been released or has not been completelyreleased, said attachment 11 is not designed to be sufficiently strongto withstand the pulling forces induced in the side panel during use.Thus, the unreleased temporary attachment 11 will most probably releasewhen the article is being worn and the product will slip down the users'waist. This might cause discomfort to the user and there is also agreater risk of leakage since the product is not kept properly in place.

As already mentioned, the temporary attachments 11 of any of theembodiments of the invention are restrained at least to an extent suchthat they withstand a pulling separating force which might arise, forexample during shipping and manufacturing. On the other hand, theyshould be sufficiently loosely restrained so that they can easily bedetached by a user without causing damage to the article or to the sidepanels themselves. To this end, any side panels 10 which comprise thereleasable attachment 11 should be designed to be releasable under aforce between about 0,5-10 N. It has been found that bonds or joins usedfor the temporary attachments 11 should have a separating strengthexhibiting a minimum resistance of 0,5 N, in order to maintain productintegrity during manufacturing and shipping, whilst user comfort andprevention of damage to the article is best ensured when forces below 10N are needed for product deployment. These forces are intended to applyto an absolute pulling force applied to a 25 mm wide sample of a sidepanel 10 temporarily attached to a surface material 2, 3 where the twomaterials are pulled apart using a peel force D at a 90° angle to thebond or join location, as depicted in FIG. 8. Still preferably, thereleasable attachments exhibit separating forces between 0,5-7 N, andstill preferably between 1-5 N. A force of 2-3N or of approximately 2 Nor approximately 3 N may be preferred. The strength of the temporaryattachment 11 may vary for side panels 10 that are wider than 25 mm, butif it is possible to find a single 25 mm sample on the side panel 10,where the force necessary to break the temporary attachments 11 fallswithin the ranges defined above, it is considered to fall within thescope of the attachment forces defined. A test method to be employed formeasuring the above delaminating separating forces may be according toASTM D 1876-72.

FIG. 3 shows an embodiment which is not according to the invention. InFIG. 3 the diaper 1 construction is the same as in FIG. 2 with thedifference that the proximal segment 13 is placed closer to the innersurface 2 of the diaper 1 and the distal segment 12 is placed fartheraway from said surface in the lap seam 14. When the user pulls A theside panel 10 to release the temporary attachments 11, the lap seam 14of the side panels breaks due to the unfavourable peel forces D in saidattachment 14.

FIG. 4 is the same type of construction as shown in FIG. 2. When theuser pulls B the side panel 10 to release the temporary attachments 11,the force exerted in the lap seam 14 is a more favourable shear force Cand said seam 14 does not break.

FIG. 5 shows an alternative embodiment of the present invention. In thisfigure a side panel is shown which has three material segments 53, 54,55 along a lateral direction x of the diaper. The most distal segment 53carries a hook fastener 16 and is placed closest towards the innersurface 2 of the diaper 1 in the lap seam 14. The more proximal middlesection 54 comprises an elastic material and is placed further away 52from the inner surface 2 of the diaper 1 than the most distal segment 53in the most distal lap seam 56 but closer 51 towards the inner surface 2than the most proximal segment 55 in the more proximal lap seam 57.

FIG. 6 shows a further embodiment according to the present invention. Inthis figure a side panel 10 is shown which has three material segments63, 64, 65 along a lateral direction x of the diaper 1. The most distalsegment 63 carries a hook fastener 16 and is placed closest towards theinner surface 2 of the diaper 1 in the lap seam 60. The more proximalmiddle section 64 comprises an elastic material and is placed farthestaway from the inner surface 2 of the diaper 1 in both lap seams 60, 61.The temporary attachment 11 is placed on the most distal lap seam 60.

FIG. 7 shows a lap seam 14 according to the present invention.

FIG. 8 shows an abutting seam 17 which does not fall within the presentinvention.

EXAMPLE

In order to show the difference in force C, D needed to separate twomaterials when using different pulling directions measurements wereconducted.

Two different sets of 5 samples were prepared. The samples all consistedof two nonwoven spunbond material segments. The first material had abasis weight of 14 gsm and is an example of a material suitable as asurface material 2 on a hygienic article 1. The second material had abasis weight of 40 gsm and is an example of a material suitable as aside panel material 10 on a hygienic article 1. The two materials of allsamples were attached to each other using a 2 mm wide line of hot meltadhesive. Of the samples five were attached with the materials in a lapseam 14 configuration as depicted in FIG. 7 which gives rise to shearforces C when the sample is pulled. The other set of five samples wereattached with the materials in an abutting seam 17 configuration asdepicted in FIG. 8 which gives rise to peel forces D when the sample ispulled. All ten samples were measured and cut into 25 mm wide materialsegments on which the tests were conducted.

The tests were conducted according to the test method ASTM D 1876-72 andmeasured on a tensile tester (any standard tensile tester can be usedfor the measurements).

The results of the test measurements were as follows:

Delamination of two layers, shear force C

Sample number Load at Peak (N) 1 7.506 2 6.636 3 6.628 4 7.466 5* NA 67.087 Mean value 7.065 *The nonwoven exemplifying a surface materialbroke before the lap seam, this sample was excluded

Delamination of two layers, peel force D

Sample number Load at Peak (N) 1 4.148 2 4.174 3 4.279 4 3.678 5 3.765Mean value 4.009

As can be seen from the results, the force required to delaminate twomaterials attached by a lap seam 14 using a shear force C is about 75%higher than if a peel force D is used. These examples clearly show theadvantage with the present invention in that the specific placement ofthe material segments in the lap seams 14 of the side panels 10 clearlyreduces the risk of unwanted breakage in the lap seam.

Although only a few embodiments of the present invention have been shownand described, it is to be understood that many changes andmodifications may be made thereto without departing from the scope ofthe invention as defined in the appended claims. Particularly, althoughthe shown embodiments have the side panels folded in toward the innersurface of the hygienic article, it is to be understood that embodimentswhere the side panels are folded towards the outer surface and attachedwith temporary attachments are also within the scope of the invention.

1. A hygienic article having an inner surface facing the user duringuse, an outer surface facing away from the user during use andoptionally an absorbent core therebetween; said hygienic articlecomprising a front waist region and a back waist region with a crotchregion connecting said front and back waist regions along a longitudinaldirection; said hygienic article comprising side panels extendingoutward in a lateral direction from either said front or back waistregion; said side panels comprising at least two material segments whichare connected to each other by a lap seam; said material segmentsdefining a distal segment and a proximal segment in the lateraldirection; said side panels each having at least one fastener at theirdistal end which fasteners are adapted to secure said side panels to thefront or back waist region such that the hygienic article assumes a pantlike shape; said side panels are folded back towards the hygienicarticle longitudinal centreline before use and attached to the inner orouter surface by at least one temporary attachment; wherein the materialsegments which form the side panels are attached to each other by thelap seam in such a way that when the side panels are folded back towardsthe longitudinal centreline of the hygienic article the materials areattached to each other in the lap seam such that the most distalmaterial segment is placed closer towards the inner or outer surface ofthe hygienic article than the proximal material segment attached to saiddistal segment and that the at least one temporary attachment issituated on the lap seam or between the lap seam and the longitudinalouter edge of the chassis.
 2. The hygienic article according to claim 1,wherein the side panels are only folded once in the lateral direction.3. The hygienic article according to claim 1, wherein each side panelcomprises at least three material segments.
 4. The hygienic articleaccording to claim 1, wherein at least one of the material segments in aside panel is a breathable material.
 5. The hygienic article accordingto claim 1, wherein at least one of the material segments in a sidepanel is an elastic material.
 6. The hygienic article according to claim1, wherein the fastening member of the side panel is a hook fastener. 7.The hygienic article according to claim 1, wherein the temporaryattachments are placed between the fastening member situated on thedistal edge of the side panel and at least 1 cm from the longitudinalside edge of the chassis.
 8. The hygienic article according to claim 1,wherein a force of 0.5-10 N is required to rupture the temporaryattachments.
 9. The hygienic article according to claim 1, wherein eachside panel consists of three material segments where the most distal lapseam has the most distal material segment placed closer to the hygienicarticle than the central material segment and the most proximal lap seamhas the most proximal material segment placed closer to the hygienicarticle than the central material segment and where the temporaryattachment is placed on the most distal lap seam or between the mostdistal lap seam and the most proximal lap seam.
 10. The hygienic articleaccording to claim 7, wherein the placement is between the fasteningmember and at least 3 cm. from the longitudinal side edge of thechassis.
 11. The hygienic article according to claim 1, wherein a forceof 0.5-7 N is required to rupture the temporary attachments.
 12. Thehygienic article according to claim 1, wherein a force of 1-5 N isrequired to rupture the temporary attachments.
 13. The hygienic articleaccording to claim 1, wherein a force of 2-3 N is required to rupturethe temporary attachments.